Answer:
I believe the answer is D.
Explanation:
Answer:
directional selection, stabilizing selection
Explanation:
Directional selection is a type of natural selection that favors one extreme phenotype over other phenotypes, thereby modifying allele frequency in the direction of the favored phenotype. This type of positive selection is the main cause of phenotypic diversification. In the USA, the environment created a selection pressure that favored individuals that don't have the defective sickle-cell allele, thereby reducing its frequency in this population. Stabilizing selection, also known as balancing selection, is a type of natural selection where the most common phenotype is selected in the population, thus predominating in future generations. In equatorial Africa, the defective sickle-cell allele is present in a high frequency because individuals that are heterozygous for this allele are less susceptible to malaria, and therefore balancing selection should maintain this allele in the African population.
Answer:
4)
Explanation:
Gametes have one haploid (n) genome, which is half of somatic cells, having one diploid (2n) genome combined through fertilization from two haploid (n) gametes.
In humans, gametes have 23 chromosomes, and somatic cells have 23 homologous pairs, which is 46 chromosomes.
Different species have different numbers, but most follow the same pattern.
Chromosomes are lined up in the middle
Ans: maintain homeostasis
Homeostasis is any
self-regulating process by which biological systems tend to maintain stability
while adjusting to conditions that are optimal for survival. It is the stable
state of an organism and of its internal environment. Maintenance of
homeostasis usually involves negative feedback loops. These loops act to oppose
the stimulus, or cue, that triggers them. The stable condition is the condition
of optimal functioning for the organism, and is dependent on many variables,
such as body temperature and fluid balance, being kept within certain pre-set
limits.